Drop Coves (Grose 1811 Dictionary)

Drop Coves

Persons who practice the fraud of dropping
a ring or other article, and picking it up before the
person intended to be defrauded, they pretend that the
thing is very valuable to induce their gull to lend them
money, or to purchase the article. See Fawny Rig, and MONEY DROPPERS.

Definition taken from
The 1811 Dictionary of the Vulgar Tongue,
originally by Francis Grose.